1. Presented byShashi Shekhar SinghSES,JNU,New Delhi

2. Identify and describe the flow of nutrients in each biogeochemical cycle Explain the impact that humans have on the biogeochemical cycles 3. An ecosystem survivesby a combination ofenergy flow and matterrecycling. 4. Nutrient Cycles: Global Recycling Global Cycles recycle nutrients through the earths air,land, water, and living organisms. Nutrients are the elements and compounds thatorganisms need to live, grow, and reproduce. Biogeochemical cycles move these substances through air,water, soil, rock and living organisms. 5. Biogeochemicalcycles are cycling of chemical elements or nutrients from the abiotic environment to organism and then back to the abiotic environment.Thepathway by which chemical circulate through ecosystem involve both living (biotic) and nonliving (geological) components.Involvedorganism (bio), environmental geology (geo) & chemical changes (chemical) 6. Most important are: The water cycle The carbon cycle The phosphorus cycle The Sulfur cycle The nitrogen cycle The circulation of chemicals in these biogeochemical cycles andinteractions between cycles are critical for the maintenance ofterrestrial, freshwater and marine ecosystems. Global climatechange, temperature, precipitation and ecosystem stability are alldependent upon biogeochemical cycles 7. There are strong forces of attraction between molecules of waterWater exists as a liquid over a wide temperature rangeLiquid water changes temperature slowlyIt takes a large amount of energy for water to evaporateLiquid water can dissolve a variety of compoundsWater expands when it freezes. 8. Water CycleRain cloudsCondensationTranspiration EvaporationPrecipitation Transpiration to landfrom plantsPrecipitationPrecipitationEvaporation Surface runofffrom land Evaporation Runoff from ocean Precipitation (rapid) to oceanInfiltration and SurfacePercolation runoff (rapid)Groundwater movement (slow)Ocean storage 9. We alter the water cycle by: Withdrawing large amounts of freshwater. Clearing vegetation and eroding soils. Polluting surface and underground water. Contributing to climate change. 10. Mining Fossil Fuels Clearing Vegetation: www.pewclimate.org/ images/figure4.gif 11. Phosphorous Cycle mining FertilizerexcretionGuano agriculture uptake by weathering uptake byautotrophs autotrophsMarine Dissolved leaching, runoffDissolvedLand Food in Ocean in Soil Water, Food Webs WaterLakes, RiversWebs death,death, decompositiondecompositionsedimentation settling outweathering uplifting over geologic time Marine Sediments Rocks 12. We remove large amounts of phosphate from the earth tomake fertilizer. We reduce phosphorous in tropical soils by clearingforests. We add excess phosphates to aquatic systems from runoffof animal wastes and fertilizers. 13. Sulfur Cycle Sulfur Water Acidic fog and Sulfuric acid precipitation trioxide Ammonia Ammonium OxygensulfateSulfur dioxideHydrogen sulfidePlantsDimethylVolcanosulfide Industries AnimalsOcean Sulfate saltsMetallic Decaying matterSulfursulfidedeposits Hydrogen sulfide 14. We add sulfur dioxide to the atmosphere by: Burning coal and oil Refining sulfur containing petroleum Convert sulfur-containing metallic ores into free metals such ascopper, lead, and zinc releasing sulfur dioxide into the environment 15. Nitrogen Cycle Legume nodule bacteria needs 10g of glucose to fix 1g of nitrogen whereasfree living bacteria require 100g of glucose to fix same amount (Odum 1983) 16. We alter the nitrogen cycle by: Adding gases that contribute to acid rain (Smil, 2000) Adding nitrous oxide to the atmosphere through farming practices (Vitousek et al., 1997) which can warm the atmosphere and deplete ozone (Chapin et al. 2002). Contaminating ground water from nitrate ions in inorganic fertilizers Releasing nitrogen into the troposphere through deforestation. 17. Effects of Human Activities on the Nitrogen Cycle Ecosystem processes can increase with nitrogenfertilization,but anthropogenic input can also result in nitrogensaturation, which weakens productivity and can kill plants(Vitousek et al., 1997) algae blooms Decreases in biodiversity both over land and in the ocean canresult if higher nitrogen availability increases nitrogen-demanding species (Aerts and Berendse 1988) NH3 in the atmosphere has tripled as the result of humanactivities. It acts as an aerosol, decreasing air quality andclinging on to water droplets (acid rain). 18. Thank You